Document Type and Number:
Japanese Patent JPS5022984
Kind Code:
B1
Abstract:
1293963 Removing acidic gases using electrolytic products IONICS INC 28 Jan 1970 [3 Feb 1969] 4027/70 Heading C7B In a cyclic process for the continuous removal of SO 2 from gaseous mixtures containing SO 2 and CO 2 , such as flue or stack gases, an aqeous solution of magnesium, ammonium or alkali metal (e.g. sodium) sulphate is fed (from line 42 via inlet 10) into the centre compartment 3 of a three compartment electrolytic cell 1 to be partially converted into an acid anolyte (e.g. Na HSO 4 ) and alkaline catholyte (e.g. Na OH) which are removed from the anode and cathode compartments 2, 5 (respectively separated from the centre compartment by porous diaphragm 4 and cation selective membrane 6) a first portion of the catholyte removed via outlet 13 is contacted with the gaseous mixtures passing up (from line 21) through scrubber 19 to absorb the SO 2 content therefrom and convert at least some of it into bisulphite (e.g. Na HSO 3 ), a second portion of the removed catholyte is passed to a carbonation tower 40 simultaneously with at least a portion of the SO 2 - free gas (from line 20) to absorb the CO 2 content and the resulting carbonated solution (containing Na 2 CO 3 and/or Na HCO 3 ) is passed as feed solution (stream 32) to the cathode compartment (via inlet 61) to improve the current efficiency of the cell. The bisulphite solution from the bottom 25 of the scrubber 19 may be combined with the acid anolyte (from outlet 8 and line 39) in a neutralizer-stripper tank 35 to reform the sulphate solution (which is recycled back as feed via line 42 and filter 47) accompanied by the desorption and subsequent recovery (via exit 44) of the SO 2 as by-product, preferably aided by a boiler 46. Part of the acid and alkaline effuent from outlets 8, 13 may be recycled via gas-liquid separation tanks 36, 16 and lines 37, 20 respectively. The porous diaphragm 4 may be of microporous rubber, ceramic, polyethylene, polypropylene or PTFE fabric. The membrane 6 may contain sulphonated and carboxylic ion-exchange groups. The anode 7 may be of Pb or Pb alloys of Ag, Sb, Te (e.g. 2% Ag and 1% Te) and/or Tl, W bronze or Pt in the form of sheet, woven screen or spaced wires or rods. The cathode 11 may be of Cu, Pb (alloy), Ni, Fe or steel. A plurality of three-compartment cells may be used. The scrubber 19 and carbonation tower 40 may be replaced by a staged absorber (A), Fig.2 (not shown) with the separate portions of the removed catholyte being passed to separate areas of the upper section of the absorber.
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Application Number:
JP710970A
Publication Date:
August 04, 1975
Filing Date:
January 28, 1970
Export Citation:
International Classes:
B01D53/50; B01D53/14; B01D53/77; C01B17/60; (IPC1-7): B01D53/14; B01D53/34; C01B17/56